Bound the TCP connect to a printer that does not answer

firmware/src/backend_anycubic.cpp

@@ -191,6 +191,10 @@ void AnycubicBackend::begin(const PrinterCfg& cfg) {
     // like to the person holding it. Nothing here is worth more than a few
     // seconds; a failed attempt is retried anyway.
     mqtt_.setSocketTimeout(4);
+    // And the TCP connect, which neither of those bounds: the client waits
+    // thirty seconds for a host that does not answer - as long as the loop
+    // watchdog - so a printer switched off restarted the box.
+    net_.setTimeout(4);
     net_.setHandshakeTimeout(5);
     mqtt_.setCallback([this](char*, uint8_t* p, unsigned int l) { onMqtt(p, l); });
     status_ = "Anycubic: connecting...";

firmware/src/backend_bambu.cpp

@@ -245,6 +245,12 @@ void BambuBackend::begin(const PrinterCfg& cfg) {
     // like to the person holding it. Nothing here is worth more than a few
     // seconds; a failed attempt is retried anyway.
     mqtt_.setSocketTimeout(4);
+    // The TCP connect has its own limit, and it is not either of the two around
+    // it: WiFiClientSecure waits THIRTY seconds for a host that does not
+    // answer, which is exactly the loop watchdog. A printer that is switched
+    // off then froze the panel for half a minute and restarted the box, again
+    // and again, until somebody turned the printer on.
+    net_.setTimeout(4);
     net_.setHandshakeTimeout(5);
     mqtt_.setCallback([this](char*, uint8_t* p, unsigned int l) { onMqtt(p, l); });
     lastTry_ = 0;

firmware/src/bambu_cloud.cpp

@@ -53,6 +53,11 @@ void open() {
     // against, the same situation as a printer on the LAN; trust comes from
     // the account session Tiger Studio obtained. See net/tls.h.
     s_net->setInsecure();
+    // The TCP connect is bounded on its own: the client's default is thirty
+    // seconds, as long as the loop watchdog, and an internet link that has gone
+    // silent would take the whole box down with it. Longer than a LAN printer's
+    // four - this is a host across the internet.
+    s_net->setTimeout(8);
     s_net->setHandshakeTimeout(5);
     // A full report from a four-unit X1 is about 50 KB and has to fit whole.
     // It lands in PSRAM - anything over 4 KB does on this build - so the size